The present invention relates in general to flush tanks for holding fluid to flush an associated water closet. The level of fluid within the flush tank is controlled by means of a ball-cock assembly which is locatable within the flush tank. In particular, the present invention relates to devices for isolating the ball-cock assembly within the flush tank from the fluid contained within the flush tank.
Recent statutory developments in many jurisdictions require water closets having any portion of the tank below the flood level rim of the closet bowl to have the ball-cock assembly installed in a separate and isolated compartment of the tank, or other approved protection.
The purpose of the protective compartment is to prevent corrosion or impact fracturing of the ball-cock fluid riser at a point below the fluid level within the flush tank. Should the integrity of the fluid riser be breached below the fluid level in the flush tank, it would be possible for the fluid in the tank and the water closet bowl itself to back-syphon into the water supply line should there be any pressure loss within the supply line itself. This back-syphoning action would present the danger of contamination within the water supply system itself.
Prior art approaches to the problem of isolating a ball-cock assembly located within a water closet flush tank from the fluids contained within the flush tank have utilize integrally formed compartments within the flush tank itself. These integral compartments are formed of the same vitreous ceramic material as the flush tank itself during the casting of the tank.
It has been found in these prior art approaches that the cast chamber is an extremely expensive addition to the flush tank itself in that the casting molds required are more complex and the yield losses due to cracking and breaking during casting and firing of the tank are substantially higher than those incurred in the production of a plain tank without the integrally formed compartment. Additionally, should the integrally formed compartment damaged during installation of the plumbing fixture, it is impossible to be repaired on the construction site.
A further disadvantage in the prior art approaches is the expense of converting pre-existing plumbing to conform to the code provisions. Thus, stock-on-hand in plumbing supply stores may not be utilized in new construction due to the lack of protection for the ball-cock riser. Additionally, the expense of the intricate tanks requires a standardized ball-cock riser due to the lack of flexiblity and adaptability of the compartment cast within the tank.